Since the bacterial cellulose is edible as well as tasteless and odorless, it is utilized in the food industry. The homogenized bacterial cellulose's high dispersibility in water further provides it with many industrial applications, such as to maintain particle sizes of food, cosmetics or coating agents, to strengthen food materials, to maintain moisture, to improve stability of food, and to be used as low-calorie additives and an emulsion stabilizer.
The bacterial cellulose is characterized by a sectional width of its fibrils which is smaller by two orders of magnitude than that of other kinds of cellulose fibers such as those derived from wood pulp.
Due to such structural and physical feature of microfibril, a homogenized bacterial cellulose has plenty of industrial applications as a strengthening agent for polymers, especially hydrophilic polymers. Products prepared by solidification of the homogenized bacterial cellulose in the form of a lump or paper show a high elastic modulus in tension owing to the above feature, and are therefore expected to have excellent mechanical properties for use in various kinds of industrial materials.
However, since an aqueous suspension or dispersion of the homogenized BC contains solvent such as water in an amount of a few to a few hundreds times the amount of cellulose component, it has some disadvantages such as the increase of space for storage, increase of the costs for storage and transportation, and decomposition of cellulose by bacteria during storage.
The present inventors have already proposed a method for drying of bacterial cellulose, comprising adding a third component other than water or BC to the aqueous BC suspension and dehydrating and drying (Japanese Patent Application Hei 7 (1995)-329472). According to this method, properties of BC such as solubility, dispesibility, precipitation degree and viscosity may be recovered when BC is returned from its dry state (water content is 25% by weight or less) to its aqueous suspension.
Although BC is used as an additive for paper, especially for the purpose of an improvement in yield on fillers, it will disadvantageously reduce its freeness in papermaking.
The present inventors have studied simple and economical methods for the production of BC having improved properties such as dispesibility, suspensibility and viscosity, so as to solve the above problems, and finally complete the present invention.